Albinism Health Article

Definition

Albinism is an inherited condition that causes a lack of pigment in the hair, skin, or eyes.

Description

People with albinism typically have white or pale yellow hair, pale skin, and light blue or gray eyes. Since their irises have little pigment, their eyes may appear pink or violet in different types of light. This is because light is being reflected from the reddish part of the retina in the back of the eye. Their skin usually does not tan and their eyes are often sensitive to light. Many have trouble with vision. Some children may be born with albinism, but develop some pigmentation as they grow older.

In albinism, the body does not produce enough of a pigment called melanin, which creates hair, skin, and eye color. Melanin protects the body by absorbing the sun's ultraviolet light. There are several types of albinism: some affect only the eyes, while others affect the skin and hair or other parts of the body.

Types of albinism

Ocular: A form of albinism that mainly affects the eyes. People with ocular albinism have some pigmentation, but may have lighter skin, hair, and eye color than other family members. Scientists have identified five different types of ocular albinism.

X-linked ocular: This type of albinism occurs mostly in males, who inherit the gene from their mothers. It causes visual disabilities.

Oculocutaneous: A type of albinism that affects the hair, skin, and eyes. Researchers have classified 10 different types of oculocutaneous albinism.

Tyrosinase-negative oculocutaneous: Also known as Type 1A, this is the most severe form of albinism, marked by a total absence of pigment in hair, skin, and eyes. People with this type of albinism have vision problems and sensitivity to sunlight. They also are extremely susceptible to sunburn.

Tyrosinase-positive oculocutaneous: People with this type of albinism have light hair, skin, and eye coloration and fewer visual impairments.

Hermansky-Pudlak syndrome (HPS): This rare type of albinism is common in the Puerto Rican community. Approximately one person in every 1,800 people in Puerto Rico will be affected by it. The lack of pigmentation can vary widely. People with HPS may have white, pale yellow, or brown hair, but it always is lighter than the rest of the population. Their eyes range from blue to brown, and their skin can be creamy white, yellow, or brown. HPS also often causes visual changes, along with other physical symptoms.

Chediak-Higashi syndrome: A rare type of albinism that interferes with white blood cells and the body's ability to fight infection.

Black Locks Albinism Deafness syndrome (BADS): Another rare form of albinism identified by a black lock of hair on the forehead. BADS causes deafness from birth.

Piebaldism: Also known as partial albinism, this condition is marked by patches of white hair or lighter skin blotches on the body.

Genetic profile

Children inherit the genes for albinism from their parents. The parents may have normal pigmentation, but if both the mother and father carry a recessive gene, there is a one in four chance their child will have albinism.

A specific genetic abnormality causes tyrosinasenegative oculocutaneous albinism (Type 1A). In this type, also called "ty-neg albinism," the body is unable to convert the amino acid tyrosine into pigment. The genes for producing the enzymes related to ty-neg albinism are located on chromosome 11 and chromosome 9.

Similarly, scientists believe the gene that causes Hermansky-Pudlak syndrome is on chromosome 10. They are studying two other genes that appear to be involved in melanin pigment formation: the P gene on chromosome 15 and the ocular albinism gene on the X chromosome.

Women who carry the gene for X-linked ocular albinism may have normal vision, but they have a one in two chance of passing it on to their sons. This type of albinism occurs mainly in males because the gene that causes it is located on the X chromosome. Since males only have one X chromosome, genetic abnormalities on this chromosome will almost always be expressed.

Demographics

Albinism affects one in every 17,000 people. All racial groups, including African-Americans and Latinos are affected by albinism. Asians have the lowest incidence of this condition.